chen@cunixc.cc.columbia.edu (Bill Chen) (03/14/89)
I've seen notes bounce around about Synoptics Lattisnet, but has anyone had experiences (good or bad) with Cabletron's twisted pair ethernet product (MMAC-3)? - Bill -- _____________________________________________________________________ William Chen chen@cunixc.cc.columbia.edu Network Planning 212-854-7593 Columbia University
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (03/16/89)
In article <1297@cunixc.cc.columbia.edu> chen@cunixc.cc.columbia.edu (Bill Chen) writes: >I've seen notes bounce around about Synoptics Lattisnet, but has >anyone had experiences (good or bad) with Cabletron's twisted pair >ethernet product (MMAC-3)? > We have had a lot of experience with Cabletron products. We have had the TP MMAC in a production environment for a month or so on a very heavily loaded Ethernet with lots of nd and nfs traffic. It works well. We have one MMAC with three TPT-MIMs as they quaintly call their modular interface cards. Almost all the interfaces are used. We have also tested their thin-coax MIM and the F/O MIM and FOTs. As many of you know, I like Cabletron very much, but I think that all the TP Ethernet products are working well and will even interoperate when the 10BaseT is finished and we have some production chips for sale. One caveat: We will not run TP Ethernet in 25 pair cable or any other sheath with tip & ring. One of our engineers has put the Cabletron TP Ethernet thru a torture test of run lengths, multiple punchdowns, tip&ring, etc and run LAN-MD tests and found no appreciable errors. It is designed to work in these existing cabling environments, but we won't be installing it in anything other than modern up-to-date individual 4 twisted pair circuits. We designed our cable plan with Ethernet in mind two years ago and I think it is exceeding our expectations, but I caution others to have old cable plants tested before making a major commitment to TP Ethernet. Following jbvb's exemplary etiquette :-) I must mention Synoptics, HP, Ungermann-Bass, David and probably many others who will have proprietary and standard implementations of TP ethernet, all of them with essentially the same performance. (no flames, please) Now, if we can just get some 10BaseT onboard transceivers, the economics should be just about right for this to really take off. Kent England, Boston University
ron@ron.rutgers.edu (Ron Natalie) (03/17/89)
I was talking to a member of the 10BaseT IEEE committee, and it was his opinion that the group was moving to what is referred to as the HP proposal (this is also what AT&T's Starlan 10 is). Neither the Synoptics nor the Cabletron twisted pair stuff is compatible with this. Something about 1MHz pilot signals or something like that. -Ron
dtk@mcdphx.UUCP (Dave) (03/29/89)
In article <1297@cunixc.cc.columbia.edu> chen@cunixc.cc.columbia.edu (Bill Chen) writes: >I've seen notes bounce around about Synoptics Lattisnet, but has >anyone had experiences (good or bad) with Cabletron's twisted pair >ethernet product (MMAC-3)? At mcdphx we have recently installed our new facility with Cabletron MMAC-3 twisted pair ethernet along with ATT wiring and pds. Our network consists of 5 MMAC-8's and 3 MMAC-3's with the Cabletron FOT fiber transceivers between buildings. We ordered the "dumb" repeater modules, but were sent and not charged for the "intelligent" repeater modules (IRM). My experience has been good with Cabletron support personnel. We had one MMAC-3 DOA, due to a power supply problem, and have had another power supply module die since installation. We have been online since 1/89. The intelligent repeater module is of limited use since no one seems to know what constitutes an error to increment on the status screen. The error could be a runt/oversize/late collision or ???. As such, it may flag a problem, but really points you to use other tools. The limits and other "features" in the IRM are disabled, and I feel of little use. During the demo of the MMAC, the entire network shutdown because the sales person had enabled the limits with very small values. As soon as the values were exceeded, the ports were disabled. Since we were not in the pds room, we tried all sorts of things before figuring out that the ports were disabled. We use a dumb terminal hooked to the IRM and not the PC based software. We have installed ~ 225 tpt2 transceivers with 5 DOA. I thought the leds would be of limited use, but they have been very useful. I am not terribly overjoyed at the number of errors reported by the IRM or by the number of errors detected by our hosts. The number is well within the 802 spec, but is a jump from our previous configuration of "mellow yellow", RG8. I guess my recommendation would be summed up in that we are buying a whole new set of Cabletron MMAC's for the old building. The biggest problem getting the network up was wiring, bad rj45 connections, and twisted pairs to/from the pds. It also is a challenge to keep an accurate picture of the pds with all the phone, rs232, and TP enet running through. We used the patch cords for maximum flexibility and I believe this to be a mistake. Our pds is very difficult to work on since all the patch cords form a large vertical pile. We use it, we abuse it, and it works for us. Dave Knappenberger dtk@mcdphx.UUCP (602) 438-3741 These are my opinions and not necessarily those of Motorola Micro Computer Division
shaver@atanasoff.cs.iastate.edu (Dave Shaver) (03/30/89)
Kent England writes: >As many of you know, I like Cabletron very much, but I think >that all the TP Ethernet products are working well and will even >interoperate when the 10BaseT is finished [...] We're (finally) moving to TP for our LANs on campus. Much has been said on the TP Ethernet issue here, but I've never really see a summary of the "whole" issue in any of the postings. Thus, I'm interested in people responding via mail and I will post a summary of the following issues and any other comments or experiences you would like to add: First, with most of the TP solutions (Cabletron, Synoptics, etc) there is one or more boxes that tie all the TP segments together (for Cabletron it's the MMAC.) A basic question we have is: What about backplane contention? Will this be a problem? e.g.: Let's say we have several diskless workstations on their own TP segment and the server on another. Assume that the server and diskless stations can be on different cards (in the Cabletron example TPT-MIMs.) Is this "slower" in any important way than if the two were connected via coax? Cabletron reps and techies claim no. We're looking for someone with experience. Next, we currently have a campus-wide "network" (read terminal server) which requires 2 pairs for a connection. However, each "network" jack on Campus has 3 pairs. Thus, a user can use the "network" and still have a pair left over. At least one department on campus has gone with Pairtamer (I think the same as a Baluns) for TP Ethernet. The Pairtamer takes RG58 and transmits it over a single pair. 3Com's sales blurbs say the segement of TP works exactly like coax, so you can do something like this without any problems: X = server x = client z = random non-client O = Pairtamer = = Coax - = Single TP =z=X===x==O------O===x==z==O-----O====x===z===O----O=z --or-- MM = Multiconnect z=O--------O=|| || z=x=O-------O=MM=O--------O=X || ||=O--------O=x==x==x I'm wondering if someone could relate their experiences with Baluns/Pairtamer vs. a "real" TP solution (Cabletron, Synoptics, etc.) All of the "real" solutions I've seen require 2 pair. In comparing the use of a "real" 2 pair solution vs. using a single pair solution (Baluns), is there enough functionality, reliability, etc, gained to warrant the major expense (on our campus) of pulling more wire to each endpoint? Cabletron reps say 2 pair solutions are the only way to go. Their major selling point seems to be in the realm of network management. Comments PLEASE. Finally, more experiences and comments (like Kent's) with either Cabletron, Synoptics, 3-Com Multiconnect, etc, are highly sought after. All of us neyphites in the TP Ethernet game thank you in advance. /\ Dave Shaver -=*=- CS Systems Support Group, Iowa State University \\ UUCP: {hplabs!hp-lsd, uunet!umix!sharkey}!atanasoff!shaver \/ Internet: shaver@atanasoff.cs.iastate.edu ...In stereo where available...